It is desirable to have a large color gamut for color printing. "Color gamut" refers to the number of colors which may be reproduced from a set of primary colors. The larger the color gamut, the more colors which can be successfully reproduced. The color gamut is a function of the chromas of the primaries. "Chroma" refers to the degree of saturation of the color. Providing high chroma primary inks will provide a large color gamut. A chroma value of a primary ink is determined by its colorant and its formulation.
Pontes et al., U.S. Pat. No. 5,100,469, disclose an ink composition comprising a colorant, a liquid carrier, and an additive selected from the group consisting of mesoerythritol and salts thereof, and RC(CH.sub.2 OH).sub.3 and salts thereof. Pontes et al. further disclose the composition may comprise from about 1.0% to about 5.0%, by weight, humectant, and that suitable humectants include glycerol, thiodiglycols, ethylene glycol, diethylene glycol and 2-pyrrolidone. Pontes et al. teach colorants may include direct dyes, acid dyes, reactive dyes and polymeric dyes.
Hotomi et al., U.S. Pat. No. 5,376,169, disclose a recording solution for ink jetting comprising pigment, resin, an additive selected from the group consisting of alginates and bomeols, and at least 55%, by weight, of a non-aqueous solvent. Hotomi et al. further teach the non-aqueous solvent may be selected from monoethylene glycol, monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, monopropylene glycol monobutyl ether, dipropylene glycol monobutyl ether, tripropyl monobutyl ether, butyl cellosolve and 2-pyrrolidone. The recording solution of Hotomi et al. may further comprise from 7% to 45%, by weight, of a compound selected from water, dithioethanol, formamide, glycerin, ethylene carbonate and methane sulfonic acid.
Gundlach et al., U.S. Pat. No, 5,531,815, disclose ink compositions comprising a betaine zwitterionic base, a quasisurfactant penetrant and, optionally, solvents such as n-methylpyrrolidione, thiodiethanol, ethylene glycol, trimethylol propane, sulfolane and glycerine.
Gundlach et al., U.S. Pat. No. 5,534,050, disclose ink compositions comprising an acetylenic polyalkylene oxide and a quasisurfactant penetrant. Gundlach et al. disclose solvents such as cyclohexyl pyrrolidione and co-solvents such as n-methylpyrrolidinone, thiodiethanol, ethylene glycol, trimethylol propane, sulfolane, and glycerine.
Nagai et al., U.S. Pat. No. 5,882,390, disclose a recording ink composition comprising a colorant which includes at least one phthalocyanine compound, a dispersant and/or surfactant, water and a humectant. Nagai et al. further disclose that humectants include water-soluble organic solvents such as diethylene glycol, thiodiethanol, polyethylene glycol, glycerol, N-methyl-2-pyrrolidinone, N-hydroxy-2-pyrrolidone, 2-pyrrolidone and 1,3-dimethylimidazolidinone.
Nagai et al., U.S. Pat. No. 5,879,439, disclose a recording ink composition comprising a colorant comprising a pigment and a polymeric dye, a dispersant and/or surfactant, water, and a water-soluble organic solvent such as diethylene glycol, thiodiethanol, polyethylene glycol, triethylene glycol, glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol, 3-methylpentane-1,3,5,-triol, 1,5-pentanediol, N-methyl-2-pyrrolidone, N-hydroxy ethyl-2-pyrrolidone, 2-pyrrolidone and 1,3-dimethylimidazolidinone.
Nagai et al., U.S. Pat. No. 5,810,915 disclose an aqueous ink composition including a dye component containing a water-soluble xanthene dye or a water-soluble phthalocyanine dye. Nagai et al. teach that the composition may further comprise water-soluble organic solvents such as diethylene glycol, thiodiethanol, polyethylene glycol, triethylene glycol, glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol, 3-methylpentane-1,3,5-triol, 1,5-pentanediol, N-methyl-2-pyrrolidone, N-hydroxy-ethyl-2-pyrrolidone, 2-pyrrolidone and 1,3-dimethylimidazolidinone.
There is a need for providing high chroma primary inks that will provide a large color gamut.